The present invention relates to a wheelchair, and more particularly, to such a wheelchair that is adapated to be driven by action of the legs of the occupant thereof.
Disabled individuals frequently use manual wheelchairs, often powering them by rotating the large wheels of the chair with their arms. This form of locomotion is quite stressful, however, due to the use of the relatively small and weak upper body musculature. In addition, decreased physical activity due to non-use of the muscles of the lower body can often lead to health problems such as poor circulation, cardiovascular disease, and the loss of calcium from bones, which then become vulnerable to fractures.
Many persons are confined to wheelchairs for reasons other than paralysis of the legs or lower body. For example, the person may be incapable of maintaining balance when in a standing position or, due to age or some other cause, may lack the necessary strength for walking. In addition, while a person may suffer paralysis, it may be limited to one leg or a portion thereof. For such persons, it would be highly beneficial to be able to make use of the muscles of the legs and lower body, to the extent they may be capable, in propelling themselves about in wheelchairs.
Additionally, as is disclosed in U.S. Pat. No. 4,421,336 issued Dec. 20, 1983 to Petrofeley et al., it has been discovered that in many cases of lower limb paralysis, it is possible to use electrical stimulation to cause the muscles of the paralyzed limbs to operate in controlled fashion. In most cases of lower limb paralysis, the motoneurons from the spinal cord to the skeletal muscles of the legs, as well as the muscles themselves, are functional. Reasons for the paralysis are usually due to loss of neuronal connections or function between the brain and the motoneurons which leave the spinal cord. If the motoneurons or the paralyzed muscles are stimulated directly by an electrical stimulator, muscular contraction will occur.
It would appear from this discovery that in the case of paralyzed individuals, the health benefits discussed above could be achieved by utilizing electrical stimulation of the leg muscles to aid in propulsion of the individual in a wheelchair.
What is needed, therefore, is a wheelchair which includes provision for propulsion by the legs of the chair occupant. Such a wheelchair could be driven in whole or in part through the use of the muscles of the legs and lower body, and could be adapted for use in conjunction with electrical muscle stimulation.